20280399 has 4 divisors (see below), whose sum is σ = 27040536. Its totient is φ = 13520264.

The previous prime is 20280389. The next prime is 20280401. The reversal of 20280399 is 99308202.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20280399 - 2¹¹ = 20278351 is a prime.

It is a super-2 number, since 2×20280399² = 822589167198402, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20280389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3380064 + ... + 3380069.

It is an arithmetic number, because the mean of its divisors is an integer number (6760134).

Almost surely, 2^20280399 is an apocalyptic number.

20280399 is a deficient number, since it is larger than the sum of its proper divisors (6760137).

20280399 is an equidigital number, since it uses as much as digits as its factorization.

20280399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6760136.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 20280399 is about 4503.3763999915. The cubic root of 20280399 is about 272.7044124576.

It can be divided in two parts, 202 and 80399, that added together give a triangular number (80601 = T₄₀₁).

The spelling of 20280399 in words is "twenty million, two hundred eighty thousand, three hundred ninety-nine".